Electronic devices typically include one or more input devices such as keyboards, touchpads, mice, or touchscreens to enable a user to interact with the device. These devices can be integrated into an electronic device or can stand alone as discrete devices that can transmit signals to another device via wired or wireless connection. For example, a keyboard can be integrated into the casing of a laptop computer. When integrated within the casing of the laptop computer, all of the components of the keyboard must be included within the casing of the laptop computer.
Conventional keyboards can provide inputs to electronic devices using a variety of input interfaces including one or more switches, buttons, actuators, or sensors (e.g., touch sensors), the actuation of which can be detect by the electronic device. In an example, the keyboard of the electronic device can include a button having a dome switch, which can be depressed to provide a detectable input. The dome switch is typically constructed by placing a conductive dome over a contact pad on a circuit board. When the dome is pressed, it may collapse such that an inner surface of the dome contacts the contact pad to form an electrical signal or input to the electronic device.
A dome switch can enclose a volume of air between the inner surface of the dome and the circuit board to which the dome is mounted. When the dome is depressed, the air within the enclosed volume needs to be displaced so that the center of the dome can contact the circuit board contact pad. Conventional key assemblies include an outer layer or membrane covering the dome switch that may allow the air to move through openings formed in the dome switch and subsequently permeate through the outer layer.
However, these openings in the dome switch and the permeable properties of the outer layer may leave the dome switch, the circuit board under the dome switch and/or the keyboard assembly vulnerable to damage. For example, water may pass through the outer layer and/or the openings formed in the dome switch and may damage the circuit board. As a result, the circuit board may be damaged or inoperable, rendering the keyboard of the electronic device partially or completely inoperable.